This invention relates to the field of golf clubs. More specifically, it relates to a "metal wood" club with an improved club head.
The goals of improving one's golf game and increasing a player's competitive advantage have led to many improvements in the design of golf clubs over the years. A relatively recent development is that of the "metal wood". Traditionally, woods (clubs usually used for tee shots and longer fairway shots) have had heads made of a hard wood, the preferred wood being persimmon. The tendency of wood to warp or split, however, coupled with increasing costs of material and labor, led to the development of metal heads for the woods. As disclosed, for example, in U.S. Pat. Nos. 4,313,607 and 4,319,752, both to Thompson, such metal wood heads typically comprise a hollow cast steel shell filled with a synthetic plastic foam material.
The metal wood has achieved a large measure of success in terms of acceptance and use by skilled golfers. Nevertheless, many golfers still prefer traditional, "wooden" woods, because of what they consider to be non-optimal weight distribution in metal wood heads. Specifically, a very important element of club head design is the concentration of as much of the mass of the head as possible into the face of the club head and the portion of the head behind the face. This puts the mass of the head where it effectively contributes to the energy imparted to the ball, rather than being merely "deadweight" that limits the velocity of the club head when it is swung. In other words, such a distribution of mass in the club head increases the effective mass of the head, without increasing its total mass. Maximizing the effective mass of the club head without significantly increasing its total mass results in little or no loss in the achievable club head velocity. The result is greater shot distance, since the energy imparted to the ball by the club is proportional to the effective mass of the club head times the square of the club head velocity.
Conventional metal woods have a substantial portion (typically about ten percent) of the total club head mass in the neck or hosel, where the head is attached to the shaft. The mass of the hosel is "deadweight" that does not contribute to the transfer of energy to the ball, but only reduces the achievable club head velocity. For example, a typical metal wood head having a total mass of about 204 grams has about 22 grams in the hosel, yielding an effective mass of about 182 grams.
Another disadvantage to conventional metal wood club heads is that the thickness of the metal shell at the face is usually insufficient to allow any appreciable degree of "shaping". "Shaping" is the grinding or machining of the face to "fine tune" its curvature to alter the type and degree of spin imparted to the ball when the ball is struck toward the heel or toe ends of the face. Proper "shaping" can counteract the hooking and slicing effects of toe and heel shots, while also allowing fine adjustments in the pitch of the club. Because there are limitations on the total mass of the club head (due to the need to maximize achievable head velocity), and because a significant portion of the mass must be apportioned to the "deadweight" of the hosel, there is little or no extra mass available for thickening the shell wall at the club face.
Another disadvantage of metal woods is that of reduced "head feel", the tactile sense of the location of the face of the club head with respect to the ball, as compared to traditional persimmon woods. This reduced head feel is the result of having the end of the shaft located in the hosel, above the club face. The effect is that the skilled player is less able to "work the ball" with the face of the club through this sense of head feel.
Thus, there has been a long-felt need for a metal wood club head with optimal mass distribution that minimizes "deadweight", while allowing greater thickness in the shell at the face, and which provides a level of "head feel" approaching that of persimmon wood club heads.